Hearing aids are electronic devices which are inserted into the middle ear compartment of the ear anatomy to amplify certain sound frequencies for improving the transmission of sound energy into the inner ear. The hearing aid is used to overcome a hearing deficiency in certain persons relating to their inability to distinguish certain audible tones, particularly at higher frequencies, within the normal audible perception range. The hearing aid is designed to be located in the middle ear cavity adjacent the ear drum. The middle ear cavity is an irregularly shaped air-filled space in the temporal bone which varies in size and shape from person to person. For proper fit and function, the body of each hearing aid is tailored to correspond in shape and size to the middle ear cavity of the patient. This is accomplished by taking an impression of the cavity of the middle ear using a silicone material or the like, and making a hollow mold from the impression to form an open shell having a shape replicating the shape of the inner ear of the patient. The amplifying electronic circuitry and battery power cell are fitted into the open shell, which is then closed with a flat plate. Alternatively, the electronics is surface mounted upon the flat plate, which is then flush mounted against the open shell to form an enclosed body with the electronics in the interior of the body. The flat plate is bonded to the shell at the mating edges of the parts. The plate is then hand trimmed by cutting off excess material extending beyond the mated edges between the plate and body. The hearing aid is then finished by polishing. The trimming, shaping and finishing operations are performed by hand to avoid damaging the body of the hearing aid. These hand operations are labor intensive, time consuming and require substantial expertise, which contributes to the high cost in the fabrication of a hearing aid.